Method of efficiently reporting user equipment transmission power and apparatus thereof

ABSTRACT

A method and an apparatus for efficiently transmitting or reporting a Power Headroom Report (PHR) of a User Equipment (UE) are provided. The method of transmitting the PHR of the UE in a mobile communication system includes configuring an extended PHR including an indicator corresponding to a variation factor of a maximum transmission power of the UE, and transmitting the extended PHR from the UE to a Base Station (BS). The BS may be notified of a maximum transmission power of the UE and a variation factor corresponding to the maximum transmission power in order to enable efficient scheduling.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of a prior applicationSer. No. 14/520,812, filed on Oct. 22, 2014, which is a continuationapplication of a prior application Ser. No. 13/400,947, filed on Feb.21, 2012, which claimed the benefit under 35 U.S.C. §119(e) of a U.S.Provisional application filed on Feb. 21, 2011 in the U.S. Patent andTrademark Office and assigned Ser. No. 61/444,844, and of a U.S.Provisional application filed on Apr. 5, 2011 in the U.S. Patent andTrademark Office and assigned Ser. No. 61/471,872, the entire disclosureof each of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of efficiently reporting UserEquipment (UE) transmission power and an apparatus thereof Moreparticularly, the present invention relates to a method of reporting UEtransmission power including a variation factor of maximum transmissionpower of a UE, and an apparatus thereof.

2. Description of the Related Art

In general, mobile communication systems have been developed to providecommunication while providing mobility to a user. Research anddevelopment of mobile communication systems has resulted in mobilecommunication systems capable of providing high speed data communicationservices as well as voice communication services with dramaticdevelopment of corresponding technology.

In recent years, research and development of standards with respect toLong Term Evolution (LTE) technology by the 3^(rd) GenerationPartnership Project (3GPP) as one of next generation mobilecommunication systems has occurred. LTE is a technology implementinghigh speed packet based communication having a maximum transmission rateof approximately 100 Mbps. In order to achieve this transmission ratefor LTE technology, various approaches have been discussed. For example,an approach of simplifying a construction or structure of a network inorder to reduce a number of nodes located along a communication line oran approach for approximating wireless protocols with respect to awireless channel have been discussed.

Meanwhile, from among an amount of bandwidth, a resource to be allottedto a data service is determined according to an amount of data to betransmitted and a channel condition, unlike a voice service.Accordingly, management operations allotting a transmission resourceconsider an amount of resources available in a wireless communicationsystem, such as a mobile communication system. These managementoperations are performed in LTE systems, which are considered to be oneof the next generation mobile communication systems, and a schedulerlocated at a base station of the LTE network manages and allots awireless transmission resource.

LTE-Advanced (LTE-A) communication systems providing improvedtransmission speeds by combining various new techniques with an LTEcommunication system has been actively researched and discussed. Amongthe various new techniques, carrier aggregation is a representativeexample of newly introduced technologies. Unlike the related art where aUE performs data transmission and/or reception using one forward carrierand one reverse carrier, according to carrier aggregation, one UE mayuse a plurality of forward carriers and a plurality of reverse carriersin the carrier aggregation. Accordingly, unlike the related art, it isnecessary to efficiently set UE transmission power for a plurality ofreverse carriers. To do this, a UE should report the UE's maximumtransmission power and available power.

Research and development of LTE communication systems allows for one UEto perform a dual mode function using a plurality of system modems.Furthermore, the UE may receive provisioning of separate services usingdifferent systems and the corresponding system modems of the UE. Thus, aUE should report a maximum transmission power and available power usedcorresponding to each system used by the UE for scheduling.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide a method that may include a variation factor ofmaximum transmission power of a User Equipment (UE) in a transmissionpower report and an apparatus thereof

Another aspect of the present invention is to provide a method capableof reporting whether a various factor of maximum transmission power of aUE is a Power management-Maximum Power Reduction (P-MPR).

In accordance with an aspect of the present invention, a method oftransmitting a Power Headroom Report (PHR) of a UE in a mobilecommunication system is provided. The method includes configuring anextended PHR including an indicator corresponding to a variation factorof a maximum transmission power of the UE, and transmitting the extendedPHR from the UE to a Base Station (BS).

In accordance with another aspect of the present invention, a method ofreceiving a PHR at a BS in a mobile communication system is provided.The method includes transmitting control information indicatingapplicability of an extended PHR including an indicator corresponding toa variation factor of a maximum transmission power of a UE to the UE,and receiving the extended PHR from the UE.

In accordance with another aspect of the present invention, an apparatusfor transmitting a PHR of a UE in a mobile communication system isprovided. The apparatus includes a controller for configuring anextended PHR including an indicator corresponding to a variation factorof a maximum transmission power of the UE, and a transceiver fortransmitting the extended PHR to a BS.

In accordance with another aspect of the present invention, an apparatusfor receiving a PHR of a BS in a mobile communication system isprovided. The apparatus includes a controller for generating controlinformation indicating applicability of an extended PHR including anindicator corresponding to a variation factor of a maximum transmissionpower of a UE, and a transceiver for transmitting the controlinformation and receiving the extended PHR from the UE.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIGS. 1A and 1B are diagrams illustrating a case where an evolved NodeB(eNB) performs undesirable scheduling according to an exemplaryembodiment of the present invention;

FIG. 2 is a diagram illustrating a procedure of transmitting andreceiving a Power Headroom Report (PHR) according to an exemplaryembodiment of the present invention;

FIG. 3A is a flowchart illustrating a method of transmitting a PHR by aUser Equipment (UE) according to an exemplary embodiment of the presentinvention;

FIG. 3B is a flowchart illustrating a method of receiving a PHR by aneNB according to an exemplary embodiment of the present invention;

FIG. 4 is a diagram illustrating a format of an extended PHR accordingto an exemplary embodiment of the present invention; and

FIG. 5 is a block diagram illustrating a configuration of a PHRtransmitting device of a UE according to an exemplary embodiment of thepresent invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

In a Long Term Evolution (LTE) system, transmission power available foruse by a User Equipment (UE) is referred to as a Power Headroom (PH),which may also be referred to as a PH value, which is defined as adifference between the UE's maximum transmission power P_(CMAX) and anamount of the UE's transmission power currently being used by the UE. Ifcertain conditions are met, the UE reports the PH value to a basestation via a Power Headroom Report (PHR). In the related art, certainconditions for reporting the PHR by the UE include when conditions of awireless path are changed by a value greater than a predeterminedthreshold value, or when a PH report period comes, i.e., a predeterminedPHR transmission interval occurs. A Base Station (BS), such as anevolved NodeB (eNB), may anticipate a channel state used by acorresponding UE based on collected PH values, and determine whether toallot additional wireless resources to a corresponding UE. Herein, theterms BS and eNB may be used interchangeably. The PH continuouslychanges due to several factors, including variation of the UE's maximumtransmission power P_(CMAX), variation of wireless path loss, or aTransmitter Power Control (TPC) command error. Due to this, the BS mayincorrectly or improperly allot wireless resources.

FIGS. 1A and 1B are views illustrating a case where a eNB performsundesirable scheduling according to an exemplary embodiment of thepresent invention.

Referring to FIG. 1A, a UE power use rate at a time t1 is illustrated. Amaximum power value P_(CMAX) _(—) H 105 and a minimum power valueP_(CMAX) _(—) L 115 of the UE's maximum transmission power P_(CMAX) 110are determined using a parameter provided by an eNB and previouslydefined parameters, such as a power range, so as to respectively be onevalue within the range.

At the time t1, the UE receives an allotment of X wireless resources ofa Resource Block (RB) and transmits data using a Modulation and CodingScheme (MCS) having a rate of m. In this case, a UE's used transmissionpower 120 is less than the UE's maximum transmission power P_(CMAX) 110.If certain conditions are met, the UE transfers a PH 145, i.e., a PHvalue, corresponding to a difference between the maximum transmissionpower P_(CMAX) 110 and the used transmission power 120 as a PHR to aneNB.

Although more wireless resources may be allotted to the UE based on thePH value, the eNB may also determine that the UE's transmission power isnot lacking. Accordingly, the eNB further allots Y RBs, and increasesthe MCS to a rate of n, which is higher than the previous rate of m, soas to provide a service with a higher transmission rate.

FIG. 1B illustrates a UE power use rate at a time t2. As illustrated inFIG. 1B, an amount of used transmission power 135 is increased ascompared to the used transmission power 120 of FIG. 1A, but a maximumtransmission power P_(CMAX) 140 is reduced so as to not influence theused transmission power 135. Accordingly, the maximum transmission powerP_(CMAX) 140 varies due to an amount and a location of a PhysicalResource Block (PRB), or a RB, a bandwidth of a system, a frequencyband, and a number of scheduled carriers.

Accordingly, according to the present exemplary embodiment, a UE reportsa maximum transmission power P_(CMAX), and a eNB collects theinformation, and considers and calculates the UE's maximum transmissionpower P_(CMAX) which is changed according to a plurality of situations.However, it is not sufficient to only collect the UE's maximumtransmission power P_(CMAX). Thus, the eNB should additionally know ordetermine what factors may cause or influence the UE's maximumtransmission power P_(CMAX) to be changed in order to have moremeaningful information.

In order to determine the factors influencing the UE's maximumtransmission power P_(CMAX), a reference value or parameter used fordetermining the UE's maximum transmission power P_(CMAX) should beacquired. As discussed above, a maximum power value P_(CMAX) _(—) H anda minimum power value P_(CMAX) _(—) L of the UE's maximum transmissionpower P_(CMAX) are determined using a parameter provided from an eNB andpreviously defined parameters, such as a power range, such that theabove noted power values are determined to respectively be one valuewithin the range.

That is, according to Equation 1, as shown below,

P_(CMAX) _(—) L≦P_(CMAX)≦P_(CMAX)H  Equation 1

where, the maximum power value P_(CMAX) _(—) H and the minimum powervalue P_(CMAX) _(—) L are defined using following Equation 2 andEquation 3.

P _(CMAX) _(—) L=MIN{P _(CMAX) −ΔTc, P _(PowerClass)−MAX(MPR+A-MPR,P-MPR)−ΔTc}  Equation 2

P _(CMAX) _(—) H=MIN{P _(EMAX) , P _(PowerClass})  Equation 3

P_(CMAX) is maximum transmission power provided from the eNB, and theinformation or value of P_(CMAX) may be provided or transmitted to theUE through a System Information Block Type 1 (SIB 1) message thatincludes broadcast information, or through any other similar or suitableinformation transmission method. Meanwhile, P_(PowerClass) is a maximumtransmission power which each UE may respectively provide. P_(CMAX) _(—)H is defined as a minimum power value of the P_(CMAX) and theP_(PowerClass).

The P_(CMAX) _(—) L is influenced by the values of a Maximum PowerReduction (MPR), an Additional-MPR A-MPR and a P-MPR, wherein ΔTc, MPR,and A-MPR are parameters defining a limit value to which a UE may adjustthe maximum transmission power P_(CMAX) so as to match the limit valuein a serving cell with respect to an adjacent channel havingpredetermined conditions affecting transmission power of the servingcell.

The MPR may be determined according to an amount of bandwidth and amodulation scheme that the UE is allotted. However, the presentinvention is not limited thereto, and other factors may be used todetermine the MPR. The A-MPR may be determined according to severalfactors, including a frequency band in which a reverse transmissionoccurs, local characteristics of a channel or a cell, and a bandwidth ofa reverse transmission. When a frequency band is sensitive to oreffected by spurious radiation at a periphery of the frequency band, theA-MPR is determined according to the local characteristics of thechannel or the cell and frequency band characteristics. When reversetransmission is performed using a channel or a frequency located at anedge of a frequency band, ΔTc is used to allow for an additionaltransmission power adjustment. When the reverse transmission isperformed at a frequency band corresponding to a bottom or lower 4 MHzof an operational frequency band or a at a frequency band correspondingto a top or upper 4 MHz, then the UE may set ΔTc to 1.5 dB. However, thepresent invention is not limited thereto, and the in other cases, the UEsets ΔTc to 0, or any other suitable value.

The P-MPR is a value by which a transmission output may be reducedaccording to Specific Absorption Rate (SAR) conditions in order tocontrol an influence of an electromagnetic wave on a human body, and maybe determined according to a distance between a device, such as the UE,and the human body. For example, when a distance between the device andthe human body is small, i.e., the device is near to the human body, atotal transmission power output value of the device should be reduced.In order to reduce the total transmission power output value of thedevice, the P-MRP is set to be a high value. On the other hand, when thedistance between the device and the human body is large, i.e., thedevice is far from the human body, the total transmission output valueof the device may be increased, and the P-MPR is set to be a small orlow value.

As shown in Equation 2, the P-MRP is related to power managementoperations of the UE. For example, when a plurality of carriers aresimultaneously operated or, in other words, the UE transmits data usingmore than one system modem, the P-MRP is used to limit the maximum powerallotted to one carrier or one system. Accordingly, it will beunderstood that, in the present exemplary embodiment, the UE's maximumtransmission power P_(CMAX) is changed according to two factorsincluding the sum of MPR+A-MPR, which is associated with out-of-bandemission requirements and a P-MPR that is associated with powermanagement.

According to the present exemplary embodiment, the UE may report anindicator, variable, or piece of information from which it is possibleto determine the applicability of the above two factors, together with amaximum transmission power. An eNB, according to the reported indicator,may determine how the UE's maximum transmission power P_(CMAX) is to bechanged according to various situations or conditions in which the UE isattempting to transmit. In the present exemplary embodiment, a method oftransferring a one bit indicator indicating a variation cause of theUE's maximum transmission power P_(CMAX) and maximum transmission powermay be used. However, the present invention is not limited thereto, andthe indicator may be transmitted as a multi-bit indicator, or may betransmitted by any other suitable means. The one bit indictor is calleda p-bit according to the present exemplary embodiment. A bit value of‘0’ for the p-bit indicates a case where the maximum transmission poweris not influenced by a P-MPR for power management, and a bit value of‘1’ for the p-bit indicates a case where the maximum transmission poweris influenced by the P-MPR for power management.

That is, in the case where the P-MPR is applied and the P_(CMAX) has adifferent value, then the p-bit is set to a bit value of 1. In a casewhere the P-MPR is not applied, if the P_(CMAX) value is the same, thenthe p-bit is set to a bit value of 0. In order to transmit the p-bit inthe PHR, an enlarged or extended PHR format may be used to includeadditional information, wherein the extended PHR is larger than arelated-art PHR. In addition to PHR trigger conditions of therelated-art, according the present exemplary embodiment, when the P-MPRis changed by a value greater than a predetermined threshold, the PHR istriggered.

FIG. 2 is a diagram illustrating a procedure of transmitting andreceiving a PHR according to an exemplary embodiment of the presentinvention.

Referring to FIG. 2, a UE 200 informs a base station, such as an eNB205, that the UE 200 may support another Radio Access Technology (RAT)or may perform Carrier Aggregation (CA) in step 210. Then, in step 215,the eNB 205 collects information corresponding to the P_(CMAX) variationfor various situations of the UE, and determines use of and configuresthe extended PHR format.

Next, the eNB 205 indicates use of the extended PHR format to the UE 200through a Radio Resource Control (RRC) Connection Reconfigurationmessage transmitted to the UE 200 in step 220. For example, the use ofor application of the extended PHR format may be indicated through aMedia Access Control (MAC)-MainConfig Information Element (IE) or otherPHR relation setting information that is included in the PHR-config IE.In step 225, the UE transmits data through another RAT or recognizesthat data transmission should occur using a plurality of serving cells,namely, an additional Secondary Cell (Scell) using a CA technology.

Next, the eNB 205 allots an uplink resource for a new transmission tothe UE 200 in step 230. In step 235, when determining the P_(CMAX), theUE 200 determines that the P_(CMAX) is influenced by the P-MPR for powermanagement, or in other words, the UE 200 determines that a powerreduction due to the P-MPR for power management is applicable to theP_(CMAX) determination. The UE 200 selects a P_(CMAX) that is within arange of a maximum value P_(CMAX) _H and a minimum value P_(CMAX) Lobtained from Equations 2 and 3, as discussed above. Next, in step 240,it is determined if at least one of following conditions is satisfied inorder for the UE to trigger the PHR.

Condition 1: when a wireless path loss value in a downlink is changed byan amount greater than a threshold value dl-PathlossChange provided fromat least one serving cell to an eNB, such as the eNB 205, in a statewhere a prohibit-PHR-Timer is expired.

Condition 2: when a periodic-PHR-Timer is expired.

Condition 3: when a PHR is for configuration and/or reconfigurationaccording to a request from an upper layer.

Condition 4: when one SCell is activated together with an uplink cell.

Condition 5: when power reverseoff by P-MPR is changed by greater than athreshold dl-PathlossChange.

Next, in step 245, if one of the Conditions 1 through 5 is satisfied,then the UE 200 reports, i.e., transmits, an extended PHR to the eNB205. The extended PHR contains a 1 bit indicator, i.e., the p-bit, forinforming of the presence of influences of the P_(CMAX) and the P-MPRtogether with PH information, i.e., the PH value, in the PHR. When amaximum transmission power is not influenced by the P-MPR for powermanagement, then the p-bit is set to a bit value of ‘0’, and when themaximum transmission power is influenced by the P-MPR for powermanagement, then the p-bit is set to a bit value of ‘1’.

For reference, when CA is applied, the extended PHR includes the PHvalue, the P_(CMAX), and the p-bit value corresponding to all activatedSCells. Here, the PH is calculated by a following Equation 4.

PH(i)=P _(CMAX,c)(i)−{10log₁₀(M _(PUSCH,c)(i))+P _(O) _(—)_(PUSCH,c)(j)+α_(c)(j)·PL _(c)+Δ_(TF,c)(i)+f _(c)(i}  Equation 4

An i-th subframe PH(i) in a serving cell c is calculated according to amaximum reverse transmission power P_(CMAX,c)(i), a number of resourceblocks M_(PUSCH,c)(i) for a Physical Uplink Shared Channel (PUSCH), apower offset Δ_(TF,c) induced from the MCS, a path loss PL_(c), and anumber of accumulated TPC commands f_(c)(i).

The PL_(c) of Equation 4 is a path loss value of a serving cell c.Furthermore, a path loss value used to determine a reverse transmissionoutput of an optional serving cell is a path loss value of a forwardchannel of a corresponding cell or a path loss value of a forwardchannel of another cell. The eNB may determine and inform the UE in acall setting procedure to use any path.

In Equation 4, the f_(c)(i) is a value corresponding to the number ofaccumulated TPC commands of a serving cell c. P_(O) _(—) _(PUSCH,C) is aparameter in an upper layer and is a sum of cell-specific andUE-specific resource blocks. In general, different values are applied tothe P_(O) _(—) _(PUSCH,C) according to PUSCH transmission types, such assemi-persistent scheduling, dynamic scheduling, and random accessresponse.

The value α_(c) is 3-bit cell-specific value provided in an upper layer.When a reverse transmission output power is calculated, α_(c) is aweight applied to path loss, wherein the higher a weight applied to apath loss is, the greater the influence on the reverse transmissionoutput power, and an applicable value is limited to α_(c) according to atype of PUSCH transmission. Additionally, in Equation 4, a j value isused to indicate a type of PUSCH, wherein j=0 indicates semi-persistentscheduling, j=1 indicates dynamic scheduling, and j=2 indicates randomaccess response.

Next, the eNB 205 stores the information included in the received PHR ina database, and uses such information for scheduling in step 250.

FIG. 3A is a flowchart illustrating a method of transmitting a PHR by aUE according to an exemplary embodiment of the present invention.

Referring to FIG. 3A, in step 300, a UE determines whether there is aninstruction to apply an extended PHR format among PHR settinginformation received from the eNB. If it is determined by the UE thatthere is no such instruction, then the UE reports the PH using a PHRformat other than the extended PHR format of the present exemplaryembodiments of the present invention in step 310.

If it is determined by the UE that there is an instruction to apply theextended PHR format, then, in step 305, the UE transmits data accordingto allotment of an uplink resource, and continuously determines whetherany of the PHR trigger conditions are met in step 315. If at least oneof the PHR trigger conditions is met, then in step 320, the UEdetermines whether a P_(CMAX) value to be reported in the PHR isinfluenced by the P-MPR in a power management side. In other words, instep 320, the UE determines whether a power reduction due to powermanagement by another RAT's transmission or SCell activation influencesthe P_(CMAX) value.

Next, if the P_(CMAX) value is influenced by the P-MPR, the UEconfigures an extended PHR in step 325, and sets a p-bit value to ‘1’ instep 330. However, if the P_(CMAX) value is not influenced by the P-MPR,then the UE configures an extended PHR in step 335, and sets the p-bitvalue to ‘0’ in step 340. Next, in step 345, the UE reports the PHR tothe eNB.

FIG. 3B is a flowchart illustrating a method of receiving a PHR by aneNB according to an exemplary embodiment of the present invention.

Referring to FIG. 3B, in step 350, an eNB collects informationcorresponding to a P_(CMAX) variation for various situations of a UE anddetermines whether to use an extended PHR format according to theexemplary embodiments of the present invention.

Next, the eNB instructs the UE to use the extended PHR format bytransmitting an RRC Connection Reconfiguration message indicating use ofthe extended PHR format. The use of the extended PHR format may beindicated through the MAC-MainConfig IE, and the PHR relation settinginformation that is included in the PHR-config IE. Next, the eNB allotsan uplink resource for a new transmission to the UE in step 370.

The eNB receives an extended PHR from the UE in step 380. As discussedabove, the extended PHR includes a 1 bit indicator, that is the p-bit,for informing the eNB of the presence of influence of P_(CMAX) andP-MPR, as well as the PH information. If a maximum transmission power isnot influenced by the P-MPR for power management, then p-bit is set to abit value of ‘0’, and if the maximum transmission power is influenced bythe P-MPR for power management, then the p-bit is set to a bit value of‘1’. For reference, when CA is applied, the evolved PHR includes the PHvalue, the P_(CMAX), and the p-bit value of all activated SCells. Next,the eNB stores information corresponding to the PHR in a database so asto be used for scheduling in step 390.

FIG. 4 is a diagram illustrating a format of an extended PHR accordingto an exemplary embodiment of the present invention.

When a PH or a plurality of PH values of a plurality of serving cells isreported in a mobile communication system in which a plurality ofcarriers are integrated or aggregated, the plurality of PH values arecollected so as to be transmitted in one PHR. Such a method oftransmitting a PHR including collected PH values may reduce a signaloverhead in comparison with transmission of each PH value by respectivecarriers, and also allows for transmission of PH values corresponding tocarriers in which there is no actual PUSCH transmission for a PHR.

Referring to FIG. 4, blocks 400 to 430 are a series of 7 bits, C1 to C7,that form a bitmap for instructing whether a PH value of a respectedactivated Component Carrier (CC) is included in a corresponding PHR.Each of the bits C1 to C7 of the bitmap corresponds to a respectiveSCell index, and, thus, corresponds to one SCell.

Block 435 is a p-bit for indicating whether a terminal's or a UE'smaximum transmission power P_(CMAX) is influenced by a P-MRP, asdiscussed above with reference to FIGS. 3A and 3B.

In a case where there is no actual PUSCH transmission, the eNB maytrigger a PHR in order to obtain path loss information for a specificreverse carrier. Furthermore, when there is no PUSCH transmission, theUE and the eNB may determine a transmission format, with respect to aMCS level of transmission resource, to be used in order to calculate aPH value. In such a case, the eNB should be notified as to whether a PHvalue of each serving cell is included in the PHR that is calculated andtransmitted with respect to an actual PUSCH transmission or whether thePHR format is transmitted using a previously defined format that doesnot include a PH value of each serving cell. To do this, a V-bit istransmitted in block 440 as an indicator for whether a PH value of eachserving cell is included in the transmitted PHR.

With respect to setting a value of the V-bit of block 440, whencalculating a PH value of an optional cell, if the calculation of the PHvalue corresponds to an actual PUSCH transmission, namely, using anactual transmission format, then the UE sets the V-bit to apredetermined value, such as a bit value of ‘0’. On the other hand, whencalculating the PH using a reference format, wherein, the number ofRBs=0, and Δ_(TF)=0, then the UE sets the V-bit to another value, suchas a bit value of ‘1’.

Block 445 corresponds to a PH value and block 455 corresponds to theP_(CMAX) value. Additionally, the PH values of each carrier are providedin a sequential order in blocks 460 to 475. Specifically, according tothe present exemplary embodiment, a Type 2 PH value of a PCell istransmitted via block 460 and a corresponding P_(CMAX) is transmittedvia block 465, and a Type 1 PH value of a SCell 1 is transmitted inblock 470 and a corresponding P_(CMAX) is transmitted in block 475.Additionally, the extended PHR of FIG. 4 includes a PH value andP_(CMAX) for each of the plurality of carriers such that a Type 1 PHvalue of SCell n is transmitted via block 480 and a correspondingP_(CMAX) is transmitted in block 485. Furthermore block 450 is for anR-bit, which is a reserved bit.

FIG. 5 is a block diagram illustrating a configuration of a UE accordingto an exemplary embodiment of the present invention.

Referring to FIG. 5, a UE 200 includes an upper layer device 510 fortransmitting and/or receiving data of an upper layer and a controlmessage processor 515 for transmitting and/or receiving controlmessages. Furthermore, the UE 200 includes a multiplexer/demultiplexer(MUX/DEMUX) 505 for performing a multiplexing and/or demultiplexingoperation when transmitting a control signal or data to the eNB 205,wherein the MUX/DEMUX 505 is operated under the control of a controller520. The UE 200 also includes a transceiver 500 for transmitting andreceiving data.

For example, when receiving data, the UE 200 receives a Radio Frequency(RF) signal via the transceiver 500 under the control of the controller520, then demultiplexes the received signal using the MUX/DeMUX 505, andthen transfers the received demultiplexed signal to the upper layerdevice 510 or to the control message processor 515 according to messageinformation of the received demultiplexed signal. Thus, according to theexemplary embodiments of the present invention, a BS, such as an eNB,may be notified of a maximum transmission power of a UE and a variationfactor corresponding to the maximum transmission power in order in orderto enable efficient scheduling.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method for transmitting a power headroom report(PHR) by a user equipment (UE) in a mobile communication system, themethod comprising: receiving configuration information comprising aprohibit PHR timer for the PHR from a base station (BS); triggering,when the prohibit PHR timer is expired, the PHR comprising an indicatorassociated with a power back-off and a maximum transmission powerdetermined in a range between a upper bound of the maximum transmissionpower and a lower bound of the maximum transmission power determinedaccording to a parameter associated with power management; andtransmitting the PHR to the BS, wherein the indicator is set to 1 if thedetermined maximum transmission power is different from a maximum powertransmission not applying the power back-off due to the powermanagement.
 2. The method of claim 1, wherein the indicator indicateswhether the UE applies the power back-off due to the power management.3. The method of claim 1, wherein the parameter is a powermanagement-maximum power reduction (P-MPR) parameter.
 4. The method ofclaim 1, wherein the configuration information comprises informationcorresponding to a configuration of the PHR, the configurationinformation being received using a media access control-mainconfiginformation element (MAC-MainConfig IE).
 5. The method of claim 1,wherein the PHR further comprises information on the maximumtransmission power, and wherein the maximum transmission power isdetermined by the UE according to a first parameter provided from the BSand a second parameter previously set by the UE.
 6. The method of claim1, wherein the indicator is set to 0 if the maximum transmission poweris not different from a maximum power transmission not applying thepower back-off due to the power management.
 7. A user equipment (UE) fortransmitting a power headroom report (PHR) in a mobile communicationsystem, the UE comprising: a controller configured: to receiveconfiguration information comprising a prohibit PHR timer for the PHRfrom a base station (BS), to trigger, when the prohibit PHR timer isexpired, the PHR comprising an indicator associated with a powerback-off and a maximum transmission power determined in a range betweena upper bound of the maximum transmission power and a lower bound of themaximum transmission power determined according to a parameterassociated with power management, and to transmit the PHR to the BS,wherein the indicator is set to 1 if the determined maximum transmissionpower is different from a maximum power transmission not applying thepower back-off due to the power management.
 8. The UE of claim 7,wherein the indicator indicates whether the UE applies the powerback-off due to the power management.
 9. The UE of claim 7, wherein theparameter is a power management-maximum power reduction (P-MPR)parameter.
 10. The UE of claim 7, wherein the configuration informationcomprises information corresponding to a configuration of the PHR, theconfiguration information being received using a media accesscontrol-mainconfig information element (MAC-MainConfig IE).
 11. The UEof claim 7, wherein the PHR further comprises information on the maximumtransmission power, and wherein the maximum transmission power isdetermined by the UE according to a first parameter provided from the BSand a second parameter previously set by the UE.
 12. The UE of claim 7,wherein the indicator is set to 0 if the maximum transmission power isnot different from a maximum power transmission not applying the powerback-off due to the power management.